Re: [PATCH v10 3/7] PCI: endpoint: pci-ep-msi: Add MSI address/data pair mutable check

[Frank Li]

On Thu, Dec 05, 2024 at 02:10:55PM +0100, Thomas Gleixner wrote:
> On Wed, Dec 04 2024 at 18:25, Frank Li wrote:
> > Some MSI controller change address/data pair when irq_set_affinity().
> > Current PCI endpoint can't support this type MSI controller. So add flag
> > MSI_FLAG_MUTABLE in include/linux/msi.h and check it when allocate
> > doorbell.
>
> Q: Who is going to annotate the affected domains with that flag?
>
> A: Nobody.
>
> Q: What's the value of the flag?
>
> A: Zero, as as it prevents exactly nothing.
>
> You want a MSI_FLAG_MSG_IMMUTABLE and set that on the domains which
> provide it. That way you ensure that someone looked at the domain to
> validate it.

Okay, at beginning I think most MSI controller is immutable. So I use
MSI_FLAG_MSG_MUTABLE.

It is fine change to MSI_FLAG_MSG_IMMUTABLE.

Frank

>
> Thanks,
>
>         tglx